The store page has Quake III: Gold requiring DirectX7 (Card with DirectX9). Will this version of Quake III work with Reshade?

No idea. Haven't tried ReShade with it.

I do have Q3 Complete on Steam though. Don't have it on GOG.

Did you check ReShade's Wiki?
Or Google around on Youtube to see if people used ReShade on it?
Or checked forums on GOG, Reddit, or Steam?

I would also check ReShade's Wiki page and see if it's in the "compatible" list:
https://www.pcgamingwiki.com/wiki/ReShade

Also, IoQuake3 is good Source Port for Q3.

Most old games in gog have these system requirements, but are NOT these for Quake III... (and are NOT for other gog games)

Quake III required as minimum:

3-D Hardware Accelerator with full OpenGL® support*
Pentium® 233Mhz MMX® processor with 8 MB Video Card
or
Pentium II 266Mhz processor with 4 MB Video Card
or
AMD® 350Mhz K6®-2 processor with 4 MB Video Card
64 MB RAM
A 100% Windows® 95/98/NT 4.0 compatible computer system (including compatible 32-bit drivers for CD-ROM drive, video card, sound card and input devices)
Windows 95/98/NT 4.0 (with Service Pack 3) operating system
25 MB of uncompressed hard disk space for game files (Minimum Install), plus 45 MB for the Windows swap file
Quad-speed CD-ROM drive (600 K/sec. sustained transfer rate)
100% DirectX 3.0 or higher compatible sound card
100% Microsoft®-compatible mouse and driver
100% Windows 95/98/NT 4.0 compatible joystick (optional)
Multiplayer Requirements
- Internet (TCP/IP) and LAN (TCP/IP and IPX) play supported
- Internet play requires a 100% Windows 95/98/NT 4.0-compatible 28.8 Kbps (or faster) modem

I mostly use IoQuake3 for Quake 3.

Of course, ain't checked IoQuake3 out w/ MP; mostly SP.

I probably should check out MP and see how active it is for IoQuake3.

It's probably a lot easier to use IoQuake3 Source Port that than say trying to fiddle around or utilize DGVoodoo or other things, to try to emulate old-school DirectX versions.

It's the same as with Q3: Gold. There are some people still playing it online, especially during weekends. The base Q3: Gold works without problems on modern hardware. It's not necessary to use third party programs. But I agree that if someone wants to play Q3 these days, he should use ioQuake 3. It's safer and has better widescreen support.

@Sarafan

Very interesting stuff. Thanks for all of the information about the MP, IoQuake3, and trying to run old-school Q3 Gold. Appreciate that.

Yeah, the specified requirements seemed unusual.

EDIT: Just in case someone else has the same question, the answer is yes. ReShade works beautifully with Quake 3, whether you play Quake 3 with IOQUAKE or Spearmint. I suggest Spearmint.

Yes, of course. I had already seen that page on PCGamingWiki for ReShade. If you look at the list, it's on the ReShade list for compatibility... but it says OpenGL.

The game is listed on the GOG store page as a DirectX game. I was hoping someone who actually plays the game can tell me if ReShade can work with this GOG version.

IoQuake3 (also OpenGL) looks like a good option, thanks for mentioning it.

If the game's info is incorrect, then I'm guessing the question is answered. Does anyone actually own the GOG version and tried using it with ReShade though? I guess I can see GOG leaving out the fact it's an OpenGL game - OpenGL works on any hardware, as far as I know. However, it really needs to be changed. Unless they made a new version, this is not true: "Graphics:
3D graphics card compatible with DirectX 7 (compatible with DirectX 9 recommended)"